贵东花岗杂岩体的稀土元素特征及与铀成矿关系

Geochemical Characteristics of Rare Earth Elements of Guidong Granitic Complex and Their Relationship with Uranium Mineralization

贵东花岗杂岩体是一个由鲁溪岩体、下庄岩体、帽峰岩体、笋洞岩体、隘子岩体和司前岩体等组成的印支—燕山期复式花岗岩体,不同的岩体不仅在主要元素含量、铝过饱和指数等方面存在差异,而且在一系列稀土元素特征方面,如稀土总量、δEu值以及LREE/HREE、(La/Yb)N、(La/Sm)N、(Gd/Yb)N比值等,也存在很大的不同。铀矿体常常赋存在强过铝质、并且后期发生了强烈的流体-岩石相互作用的花岗岩体中,这些岩体典型的稀土元素特征是稀土总量、δEu、LREE/HREE、(La/Yb)N、(La/Sm)N、(Gd/Yb)N比值等均较低,并具有M型四分组效应。

The Guidong granitic complex is constituted by Luxi pluton, Xiazhuang pluton, Maofeng pluton, Sundong pluton, Aizi pluton and Siqian pluton, which intruded in Indosinian and early Yanshanian Periods. These plutons varies from each other not only in major element content, aluminium saturation index, but also in ∑REE, δEu, and LREE/HREE, （La/Yb）N, （La/Sm） N and （Gd/Yb） N ratios. Uranium mineralization is mainly hosted by strong peraluminous granites, which has undergone intense fluid-rock interaction, and their REE compositions are characterised by M-type tetrad effects and lower ∑REE, δEu value, LREE/HREE, （La/Yb）N, （La/Sm）N and （Gd/Yb）N ratios.